When a heat exchanger is employed as an evaporator, it is important to keep all surfaces wetted so that a maximum heat transfer effect occurs between the wetted surfaces and the liquid in order to create bubbles or boiling by the vapor action. As is well known in the field or refrigeration, when an evaporator is covered or filled with a liquid which is boiled by having heat applied to it, through the heat exchanger surfaces, then the liquid itself has much higher density, usually, than the vapor which is created by boiling.
The design of a flat plate heat exchanger may very readily be along the general lines of the heat exchangers shown in applicant's copending application Ser. No. 846,318 filed Oct. 28, 1977. In said application, there is disclosed a unique construction for a flat plate exchanger specifically adapted for condensing or boiling fluids in sea thermal power plants. In addition, applicant's prior U.S. Pat. No. 3,312,054 dated Apr. 4, 1967, deals with heat exchangers in conjunction with a sea water power plant.